Polycarbonate is known as a thermoplastic resin which is robust and transparent, and has high impact resistance. However, polycarbonate also has relatively high melt viscosity. Therefore, so as to prepare molded products using polycarbonate, relatively high extrusion temperature and molding temperature are required. Over the years, considerable effort has been made to maintain preferable physical characteristics while reducing melt viscosity of polycarbonate. With regard to this, a plasticizer is used, an aliphatic chain stopper is used, a molecular weight is reduced, or a blend of bisphenol having a long-chain aliphatic substituents and a variety of polycarbonate copolymers, and a blend of polycarbonate and other polymers are prepared.
With regard to use of plasticizers, plasticizers are generally used with a thermoplastic resin to achieve greater melt flowability. However, when a plasticizer is mixed with a polycarbonate composition, the plasticizer exhibits undesirable characteristics such as brittleness and changeability.
When an aliphatic chain stopper is used, flowability may be easily and properly obtained but impact resistance, which is measured using notched Izod, is considerably deteriorated. In addition, brittleness may be a problem.
When bisphenol having an aliphatic long-chain is used, increase of flowability may be observed. However, considerable reduction of desirable impact strength characteristics is generally associated therewith.
Therefore, there is a need to develop polycarbonate having high fluidity.